In some diagrams, whether the arrow marked lines are parallel?
I have a sheet of questions on circle theorems. I did most of them but some of them I don't know what to do.
I know the basic rules:
1) The angle at the centre of the circle is double the angle at the circumference standing on the same arc
2) The angle in a semicircle is right angle or 90 degrees
3) Angles at the circumference of the circle standing on thee same arc are equal
4) The opposite angles of a cyclic quadrilateral are supplementary.
I haven't got up to tangent and chords yet. Just these for now.
Thanks in advance!!